Jet-injection hypodermic device



June 2, 1970 JIROMARU TSUJINO 3,515,130

JET-INJECTION HYPODERMIC DEVICE 4 Sheets-Sheet 1 Filed Sept. 18, 1967 JIROMARU TSUIINO,

INVENTOR.

BY mm. W M

'Fmal. MW

JIROMARU TSUJ INO 3,515,130 JET INJECTION HYPODERMIC DEVICE June 2, 1970 4 Sheets-Sheet 2 Filed Sept. 18, 1967 FIG. 3

ACCUMJLATOR+ PRESSURE SWITCH \FIG.

IIROMARU TSUJ'INO.

INVENTOR.

BY UM. l mak. MW

June 2, 1970 JIROMARU TSUJINO 3,515,130

JET-INJECTION HYPODERMiC DEVICE Filed Sept. 18, 1967 I 4 Sheets-Sheet :5

.TIROMARU TSUIINOI INVENTOR.

BY WM. 0AA

June 2, 1970 JIROMARU TSUJINO 3,515,130

JET-INJECTION HYPODERMIC DEVICE 4 Sheets-Sheet 4 Filed Sept. 18, 1967 FIG. 8

FIG. 9

' IIROMARU TSUIJNO,

INVENTOR.

BY wmmhwb M1,

PM. MM}

United States Patent Oflice Patented June 2, 1970 3,515,130 JET-INJECTION HYPODERMIC DEVICE .Iiromaru Tsujino, Tokyo-t0, Japan, assignor to Kabushiki Kaisha Yuryo Kikakuhin Kenkyusho, Tokyo-t0, Japan Filed Sept. 18, 1967, Ser. No. 668,381 Claims priority, application Japan, Sept. 21, 1966, 41/ 61,934 Int. Cl. A61m /30 US. Cl. 128173 7 Claims ABSTRACT OF THE DISCLOSURE This invention relates to fluid injection devices, particularly to hypodermic injection devices, and more particularly to a new and improved hypodermic injection device of jet-injection type capable of injecting instantaneously a specified quantity of a liquid into a part of a human or animal body without the use of a hypodermic needle.

Hypodermic injection devices of this character have simple operation and are capable of injecting a large number of persons in a short time. Accordingly, these devices are considered to be optimum means for purposes such as preventive inoculation or immunization programs.

Injection devices of the type referred to above have heretofore been used or proposed. In almost all cases, however, these devices have been accompanied by difliculties such as heavy weight, bulkiness, and complicated organization.

In one jet-injection device proposed heretofore, the injector contains a main spring which is compressed and cooked by hydraulic pressure and then released, the energy thus released being utilized to operate a plunger pump for ejection of injection liquid. For effective operation, the mass of the main spring, piston, and other moving parts of this injector necessarily are substantially large and not only add to the weight of the entire injector but also reduce the injection velocity. Furthermore, the quantity of injection liquid for each dose is adjustably varied by the procedure of changing the compressed length of the main spring, which procedure is somewhat diflicult.

It is an object of the present invention to provide improvements in jet-injection type hypodermic devices.

More specifically, an object of the invention is to provide a jet-injection hypodermic device having an injector of compact, simple construction and light weight.

Another object of the invention is to provide a jetinjection type injector in which hydraulic pressure is used to drive directly a piston pump for ejecting injection liquid, whereby an almost constant driving force can be imparted to the pump piston, and the ejection pressure can be readily varied to suit the injection conditions.

Still another object of the invention is to provide a jet-injection type injector in which the quantity of injection liquid dose can be readily and accurately varied by merely rotating a ring around the injector body.

A further object of the invention is to provide a jetinjection type injector of even lighter weight afforded by elimination of hydraulic system valves in the injector body, which injector, moreover, is connected to the hydraulic pressure supply system of the device by only a single hydraulic line and three thin electrical conductors.

According to the present invention, briefly summarized, there is provided a jet-injection hypodermic device consisting essentially of a hydraulically operated injector, hydraulic pressure means connected to and supplying hydraulic pressure to the injector, and hand operated control means to control the hydraulic pressure means, the injector comprising an injector head containing a piston pump for drawing in injection liquid through an inlet and ejecting the liquid through a fine ejection orifice, a hydraulic cylinder formed in the injector and containing a hydraulic piston with a piston rod coupled to the piston of the piston pump, the hydraulic piston being driven in one direction for ejecting the injection fluid by hydraulic pressure and in the opposite direction for drawing in injection liquid by a return spring, and at least a hand operated part of the control means.

The nature, principles, details, and utility of the invention will be more clearly apparent from the following detailed description with respect to preferred embodiments of the invention when read in conjunction with the accompanying drawings, in which like parts are designated by like reference numerals and characters.

In the drawings:

FIG. 1 is a side elevational view, with parts cut away and with some parts in longitudinal section, showing one example of an injector of the hypodermic injection device according to the invention;

FIG. 2 is a cross sectional view taken along the plane indicated by line IIII in FIG. 1;

FIG. 3 is a schematic diagram showing one example or organization of a hydraulic system for actuating the hypodermic injector according to the invention;

FIG. 4 is an enlarged, fragmentary perspective view, with parts cut away, showing one arrangement of the valve mechanism of the injector shown in FIG. 1;

FIG. 5 is a view, similar to FIG. 4, showing another example of the valve mechanisms;

FIG. 6 is a partial side elevational view showing the rear part of an injector provided with the valve mechanisms shown in FIG. 5;

FIG. 7 is a view, similar to FIG. 5, showing still another arrangement of the valve mechanism;

FIG. 8 is a partial side elevational view showing the rear part of an injector provided with the valve mechanism shown in FIG. 7;

FIG. 9 is a partial side elevational view showing the rear part of a further example of an injector according to the invention; and

FIG. 10 is a schematic diagram showing another example of a hydraulic system for actuating the injector.

Throughout this disclosure, directional terms such as front and rear respectively designate the injection end and hydraulic line connection end of the injector (i.e., the left and right ends as viewed in FIGS. 1, 6, 8, and 9).

Referring first to FIG. 1, the example shown therein of an injector according to the invention has an injector body 1 provided with a hollow cylindrical interior constituting a hydraulic cylinder 1a, in which a hydraulic piston 2 is slidably disposed. The front part of the hollow interior 1a is relatively enlarged in diameter and is provided with internal screw threads 1b.

A front cap cylinder 3 consisting of a large-diameter cylindrical part 3a at the front and a small-diameter cylindrical part 3b coaxially to the rear is disposed forward of and coaxially with the front part of the hollow interior 1a. The large-diameter cylindrical part 3a is provided with diametrically opposed through holes 4, 4. The small-diameter cylindrical part 3b is provided with diametrically opposed through slots 5, 5 formed in the longitudinal direction. The rear skirt part of the cylindrical part 3b is provided on its outer surface with external screw threads which are screwed into the above mentioned internal screw threads 1b.

An adjusting ring 6 is fitted around the slotted front part of the small-diameter cylindrical part 3b in a circumferentially rotatable manner and is interposed slidably between the rear shoulder face of the part 3a and the front end face of the body 1. The adjusting ring 6 is provided with internal screw threads 6a.

The aforedescribed hydraulic piston 2 is fixed to a forwardly extending piston rod Zn, on which a spring retainer 7 is fitted in an axially slidable manner. The spring retainer 7 has radially extending, opposed lugs 7a and 7b which are slidably engaged with respective slots 5, 5 in the part 3b of the front cap cylinder 3 as shown in FIG. 2 and which are provided at their outer peripheries with external screw threads screw engaged with the internal threads of the adjusting ring 6. Accordingly, when the adjusting ring 6 is rotated, the spring retainer 7 is caused to slide along the piston rod 2a in the axial direction as it is guided and prevented from rotating by the slots 5, 5.

A compression coil spring 8 disposed around the rear part of the piston rod 2a is interposed between the piston 2 and the spring retainer 7. The piston rod 2a is provided at a position forward of the spring retainer 7 with a stop member 10 fixed to the piston rod 2a and having radially extending lugs slidably engaged with respective slots 5, 5 of the front cap cylinder 3. The front end of the piston rod 2a extends forward through a hole in the front wall 11 of the front cap cylinder 3.

The front cap cylinder 3 supports an injector head 12 inserted at its rear base end into a recess 11a in the front wall 11 of the cylinder 3 and mounted securely in position by a nut 13 screwed onto external threads provided on the front wall 11. The injector head 12 is provided with a hollow cylinder bore 14 at its rear part, an ejection orifice 15 communicating coaxially with the cylinder bore 14, and an inlet 16 for an immunization or medicative liquid also communicating with the cylinder bore 14, the injection liquid being supplied by a container (not shown).

The cylinder bore 14 contains therewithin a pump piston 17 to operate cooperatively therewith to accomplish pumping action. This piston 17 is fixed to a piston rod 1701, the rear end of which is fixed to the front end of the aforementioned piston rod 2a.

The ejection orifice 15 and the inlet 16 are provided respectively with check valves 18 and 19 permitting passage of the injection liquid to be administered only in the administering direction. I have found that it is preferable to form the orifice 15 in a nozzle piece 20 made of a hard material and fitted into the front extremity of the injector head 12.

The hydraulic cylinder 1a communicates through its rear head and by way of a valve mechanism 30, constituting an important element of the invention, to a hydraulic fluid supply line 21 and a hydraulic fluid discharge line 22, which are made of flexible tubing material.

When pressurized hydraulic fluid is introduced into the cylinder 1a within the body 1 through the valve mechanism 30, in a manner described more fully hereinafter, the hydraulic piston 2 is forced to slide forward, overcoming the force of the compression spring 8. This movement of the piston 2 is transmitted through the piston rods 2a and 17a to move forward the pump piston 17, whereby an injection liquid which has been drawn into the injector head 12 is ejected through the ejection orifice at a high velocity in the form of a jet which, when the front face of the nozzle piece 20 is being pressed against a body part, penetrates the outer skin and enters the body tissues.

When the hydraulic pressure within the cylinder 1a is released as described hereinafter, the hydraulic piston 2 is moved rearward by the force of the spring 8, whereby the pump piston 17 within the injector head 12 also moves rearward. If, at this time, the inlet 16 is communicating with means (not shown) for supplying an injection liquid, the injection liquid will be drawn into the interior of the injector head 12.

The rearward movement of the hydraulic piston 2 is stopped when the stop member '10 fixed to the piston rod 211 contacts and is stopped by the spring retainer 7. Therefore, by rotating the adjusting ring 6 to adjustably set the axial position of the spring retainer 7, it is possible to adjust the quantity of injection liquid drawn into the injector head 12 for the subsequent injection.

The hydraulic pressure for operating the above described injector is supplied to the hydraulic cylinder 1a through the valve mechanism from a hydraulic fluid supplying and discharging system connected to the rear extremity of the injector body 1 through the hydraulic lines 21 and 22, one example of the system being shown in FIG. 3.

In this system, hydraulic fluid in a reservoir 80 is drawn through a strainer 73 by a pump 74 driven by a motor M and is pressurized. Excessive increase in the pressure of the fluid on the delivery side of the pump 74 is prevented by a safety valve connected to the delivery line. Along this delivery line, there are connected, in sequence, a pressure switch 76, an accumulator 77, and a safety device 78 for operating cooperatively with the accumulator 77 or the pressure switch 76 to block the passage of the hydraulic fluid when the pressure thereof is below a predetermined value. The hydraulic fluid under specified conditions which has passed through the safety device 78, passes through the supply line 21 and is supplied into the valve mechanism 30, through which the fluid passes, when an inlet valve V1 is opened as described hereinafter, and enters the hydraulic cylinder 1a.

A check valve 81 is preferably placed in the hydraulic supply path between the hydraulic supply line 21 and the inlet valve V1 to prevent reverse flow of the hydraulic fluid.

Hydraulic fluid discharged from the hydraulic cylinder 1a passes through a discharge valve V2 in the valve mechanism 30, the discharge line 22, and a throttle device 79 to return to the reservoir 80. The throttle device is readily adjustable for adjusting its degree of throttling thereby to adjust the return flow-rate of the hydraulic fluid.

The details of organization and operation of the valve mechanism 30 and related parts will now be described with reference to FIGS. 1 and 4. As indicated in FIG. 1, the valve mechanism 30 is of built-in construction disposed within the injector body 1 at its rear end and has an inlet valve V1 and a discharge valve V2 spaced apart in the longitudinal direction as shown in FIG. 4.

The inlet valve V1 includes and is assembled in a cavity in the ejector body 1, which cavity consists essentially of a small-diameter cylindrical chamber 31 and a largediameter cylindrical chamber 32 in coaxial, contiguously communicating alignment on an axis perpendicular to the longitudinal direction of the ejector body 1. A stepped shoulder 33 formed at the junction between these chambers 31 and 32 to function as a valve seat.

The small-diameter chamber 31 contains a valve actuating rod 34 consisting of an upper (as viewed in FIGS. 1 and 2) part 34a of a diameter for sliding within the chamber 31 and a lower part 34b of smaller diameter. The valve actuating rod 34 can thus slide within the chamber 31. The large-diameter chamber 32 is closed at its outer end (lower end as viewed in FIGS. 1 and 4) by a plug screw 35 having a projection on its inner end, On which one end of a compression spring 36 is held. The other end of the spring 36 holds and presses with spring force a valve ball 37 toward the aforementioned shoulder 33 which constitutes a valve seat.

In the normal state of the valve V1, the ball 37 is pressed against the shoulder 33 by the spring 36-, thereby shutting off communication between the chambers 32 and 31, and the upper end of the valve actuating rod 34 projects out beyond the upper surface of the injector body 1, the lower end of the rod 34 resting on the upper side of the ball 37.

The middle part of the chamber 31 of the valve V1 is communicatively connected to the hydraulic cylinder 1a through a passage 38 formed in the injector body 1. On the other hand, the chamber 32 is communicatively connected to the hydraulic supply line 21 through a passage 39 formed in the injector body 1.

A sliding rod 40'is disposed slidably in a hole through the injector body 1 in a parallel, transversely side-by-side relationship to the inlet valve V1.

The discharge valve V2 has the same construction as the inlet valve V1 but has an orientation which is inverted relative to that of valve V1. For the sake of clarity of illustration, the inlet and discharge valves V1 and V2 are shown in FIG. 4 as being spaced apart with a distance therebetween which is greater than that in the actual valve mechanism 30. Similarly as the inlet valve V1, the discharge valve V2 comprises a small-diameter chamber 41, a large-diameter chamber 42, a shoulder 43 constituting a valve seat, a valve actuating rod consisting of a sliding part 44a and a part 44b of smaller diameter, a compression spring 46, a valve ball 47, and other minor parts. The chamber 42 and 41 are respectively communicated with the hydraulic cylinder 1a and the hydraulic discharge line 22 through passages 48 and 49, respectively, formed in the injector body 1.

The valves V1 and V2 are controllably operated by a valve control lever 50 pivotally mounted at its rear end on the injector body 1 by a pivot pin 51 having a transverse axis at the rear end of the injector body 1. The valve control lever 50 has an inverted U-shaped cross section at its rear pivoted end, which straddles the upper part (as viewed in FIG. 1) of the rear end of the injector body 1, and extends toward the front of the injector body. The control lever 50 thus has an operational stroke between an outer position away from the injector body 1 and an inner position closer to the injector body and is normally forced to assume the outer position by a leaf spring 51a interposed between the lever 50 and the injector body 1.

At the rear end of the injector body 1 and on the side thereof opposite the valve control lever 50, there is provided a leaf spring 52 fixed at its rear end by a pin 53 to the rear extremity of the injector body 1 and normally disposed parallelly against the lower surface of the injector body.

The lower end of the aforementioned sliding rod 40 is resting in contact with the upper surface of the leaf spring 52 as shown in FIG. 4. In this normal state, the upper end of the sliding rod 40 is projected upward to a higher position than the upper end of the valve actuating rod 34 of the inlet valve V1. Furthermore, the leaf spring 52 in its normal state is in contact with the lower end of the part 4401 of the valve actuating rod of the discharge valve V2. Consequently, the ball 47 of the discharge valve V2 is separated from its valve seat formed by the shoulder 43.

The valve control lever 50 is provided with a projection 53 fixed to the lower surface of the lever 50 at a position somewhat forward of the pivot pin 51 and confronting the upper ends of the sliding rod 40 and the valve actuating rod 34 of the inlet valve V1.

The valve mechanism 30 of the above described organization operates in the following manner.

When the valve mechanism 30 is in the normal state, that is, when the injector is inoperative, the valve control lever 50 is maintained in its outer position by the leaf spring 51 as mentioned hereinbefore, and the inlet valve V1 of the valve mechanism is closed to shut off communication between the hydraulic supply line 21 and the hydraulic cylinder 1a, the discharge valve V2 then being open to provide communication between the hydraulic cylinder 1a and the hydraulic discharge line 22. The hydraulic piston 2 at this time is in its rearward retracted position, and it will be assumed that an injection liquid has been drawn into the injector head 12.

Then, when the operator grips the injector and squeezes the valve control lever 50 toward its inner position, the lower surface of the projection 53 first contacts the upper end of the sliding rod 40 at the higher position and depresses the rod 40 downward as viewed in FIG. 4, whereby the lower end of the sliding rod 40 deflects the leaf spring 52 downward, countering its elastic force. Consequently, since the part of the leaf spring 52 contacting the lower end of the valve actuating rod 44 of the discharge valve V2 is thereby displaced downward, the ball 47 of the discharge valve V2 is pressed against the valve seat 43 by the force of the spring 46, thereby closing the discharge valve V2 and shutting off communication between the hydraulic cylinder 1a and the hydraulic discharge line 22.

Then, as the valve control lever 50 is squeezed further, the lower surface of the projection 53 contacts and depresses downward the upper end of the valve actuating rod 34 of the inlet valve V1, whereby the lower end of the rod 34 pushes the ball 37 downward, counter to the force of the spring 36, thereby to open the inlet valve V1 and establish communication between the hydraulic supply line 21 and the hydraulic cylinder 1a. Consequently, hydraulic fluid is introduced into the hydraulic cylinder 1a, but since the discharge valve V2 is closed as described above, hydraulic pressure is imparted to the hydraulic piston 2 to cause the injection liquid in the injector head 12 to be ejected. The terminal point of the stroke of the valve control lever 50 is determined by the contact of the projection 53 against the outer surface of the injector body 1.

Upon completion of one cycle of injection operation, the operator releases his grip on the valve control lever 50, whereupon the lever 50 is returned by spring 5 1 to its original position. During this return stroke of the lever 50, the lower surface of the projection 53 releases the upper end of the valve actuating rod 34 thereby to close the inlet valve V1 and shut olf the supply of hydraulic pressure to the hydraulic cylinder 1a. Next, the upper end of the sliding rod 40 is released, whereby the leaf spring 52 is permitted to return to its original position, and the force of this spring 52 is thereby released to push the ball 47 upward to open the discharge valve V2. Consequently, the interior of the hydraulic cylinder 1a is communicated with the hydraulic discharge line 22, and the hydraulic fluid within the cylinder 1a is forced by the hydraulic piston 2 retracted by the force of compression spring 8 to be discharged through the discharge line 22 and throttle device T (FIG. 3) and return to the reservoir 80.

When the valve control lever 50 is in a position such that the lower surface of the projection 53 is depressing only the upper end of the sliding rod 40 and is not depressing the valve actuating rod 34 of the inlet valve V1, the inlet and discharge valves V1 and V2 are both closed. Therefore, by holding the valve control valve 50 in this position, the hydraulic fluid is retained in the hydraulic cylinder 1a, and the injection operation can be temporarily stopped.

Another example of the valve mechanism and valve control lever is illustrated in FIGS. 5 and 6, in which the inlet and discharge valves V1 and V2 are disposed trans- Versely in a plane perpendicular to the longitudinal direction of the injector body 1 and are directed in mutually opposite directions as in the previous example, Furthermore, the construction of each of these valves V1 and V2 is exactly the same as that of the corresponding valve in the previous example and, therefore, will not be described in detail. The large-diameter and small-diameter 7 chambers of inlet valve V1 communicate respecetivly with the hydraulic supply line 21 and the hydraulic cylinder 1a, while the large-diameter and small-diameter chambers of discharge valve V2 communicate respectively with the hydraulic cylinder 1a and the hydraulic dis charge line 22.

As shown in FIGS. 5 and 6, the valve control lever 50A has a rear proximal end having a substantially deep inverted U-shaped cross section and straddling the rear end of the injector body 1, on which the rear end of the lever 50A is pivoted at 51A. The valve control lever 56A is urged toward the outer position of its stroke by a leaf spring 51A similarly as in the aforedescribed example.

The inner surfaces of the side flange parts of the rear U-shaped end of the valve control lever 50A are provided respectively with earns 60 and 61 fixed thereto and adapted to contact and impart cam action to the outer ends of the valve actuating rods of valves V1 and V2, respectively. When the valve control lever 50A is in its normal outer position, the surface of cam 60 is not in contact with the outer tip of the valve actuating rod of inlet valve V1, whereas the surface of cam 61 is pressing and holding the tip of the valve actuating rod of discharge valve V2 in an inward position against the force of the valve spring, whereby the ball of the valve V2 is separated from its valve seat. Accordingly, the inlet valve V1 is closed, and the discharge valve V2 is open.

The surface of cam 60, as shown in FIG. 5, progressively increases in cam height toward the tip of the valve actuating rod from the lower part of the cam surface to the upper part thereof. That is, the surface of cam 60 slopes upward and inward. The surface of cam 61 proressively decreases in cam height in the upward direction.

When the operator grasps the injector and squeezes the valve control lever 50A, and the cams 60 and 61 thereby descend, the surface of cam 61 progressively recedes and permits outward displacement of the valve actuating rod of discharge valve V2 until, finally, valve V2 is closed, whereby passage of hydraulic fluid from the hydraulic cylinder 1a to the hydraulic discharge line 22 is blocked.

Then, as the valve control lever 50A is squeezed further, the surface of cam 60 begins to contact the tip of the valve actuating rod of inlet valve V1 and progressively displaces the valve actuating rod inward, thereby opening valve V1. Accordingly, hydraulic fluid is supplied through inlet valve V1 into the hydraulic cylinder 1a to force the hydraulic piston 2 forward.

When the valve control lever 50A is released, the force of leaf spring 51Aa causes the lever 50A to return to its normal outer position, and the above described operation is reversed, whereby inlet valve V1 is closed, and then discharge valve V2 is opened.

In still another example of the valve mechanism according to the invention as illustrated in FIGS. 7 and 8, the inlet and discharge valves V1 and V2 are disposed vertically in side-by-side arrangement in a plane perpendicular to the longitudinal direction of the injector. The construction of each of the valves V1 and V2 is the same as that in the aforedescribed two examples, and the two valves are directed in mutually opposite directions.

In this example, the valve control lever 50B at its rear proximal end is pivoted at pivot 51B on the rear end of the injector body 1 and is urged toward its normal outer position by a leaf spring 5113a similarly as in the preceding examples. The rear proximal end of this valve control lever 50B, however, has a cross section in the shape of a fully closed figure. The rear proximal end, therefore, is in the form a tube 70 which in the example illustrated is of substantially rectangular cross section with rounded corners, and which encompasses the rear end of the injector body 1. The upper and lower inner surfaces 71 and 72 of this tube 70 are adapted to operate the valves V1 and V2 in the following manner.

When the valve control lever 50B is in its normal outer position, the upper inner surface 71 is separated from 8 the outer tip of the valve actuating rod of the inlet valve V1, whereas the lower inner surface 72 is pressed against the outer tip of the valve actuating rod of the discharge valve V2 and is holding the rod in its inwardly displaced position. Accordingly, in this normal state, the inlet valve V1 is closed, and the discharge valve V2 is opened.

When valve control lever 50B is squeezed toward injector body 1, lower surface 72 descends and permits discharge valve V2 to close. Then, as lever 50B is squeezed further, upper surface 71 contacts and depresses the valve actuating rod of valve V1, whereby valve V1 is opened, and hydraulic fluid is supplied into hydraulic cylinder 1a to force hydraulic piston 2 forward.

When valve control lever 50B is released, the above described operation is reversed to close inlet valve V1 and open discharge valve V2.

As described above with respect to specific examples, the present invention provides a jet-injection hypodermic device in which a jet type injector is connected through a unique valve mechanism to a hydraulic pressure supply system, and the valve mechanism, moreover, is built in in one part of the injector itself, whereby the injector, at the time of its use, can be connected to the hydraulic pressure system with only two simple lines made of flexible tubing.

Furthermore, the chambers and passages of the valve mechanism can be readily formed in the injector body by simple operations such as boring, and the entire valve mechanism can be made extremely small, whereby the injector itself can be made light and compact.

A further feature of the injector according to the invention is that the inlet valve V1 and discharge valve V2 of the valve mechanism can be respectively opened and closed in a specific sequence merely by a simple, onehand operation of squeezing and releasing a valve controlling mechanism to cause displacements of the hydraulic piston. Accordingly, the controllable operation is extremely simple and reliable, and injection and drawing in of the injection liquid can be readily interrupted.

While the throttle device 79 can be placed at any point between the outlet of the discharge valve V2 and the reservoir 80, it is preferable to install this device within the rear end of the injector body 1. For example, although not shown, an adjusting screw can be provided to pass through the injector body 1 from its side and project into the passage 49 of the example shown in FIG. 4, the degree of projection of the tip of this adjusting screw being varied by turning the screw thereby to adjust the degree of throttling.

In a further embodiment of the invention as illustrated in FIGS. 9 and 10, the construction of the injector is essentially the same as that of the injector shown in FIG. 1 except for the absence of a valve mechanism in the structure of the injector, the connection of a single hydraulic line 21a to the rear end of the injector body 1, and the provision of an electrical control switch device 23 on the outer surface of the injector body 1.

The electrical control switch device 23 comprises a con tact 23a operated by control actuating movements in the radial direction of the injector body 1 and a contact 23b operated by control actuating movements in the longitudinal direction of the injector body. The control switch device 23 is connected to and constitutes a part of an electrical control circuit for controlling the operation of a hydraulic pressure supply system of the following organization. The control switch device 23 on the ejector can be thus connected to the other parts of the control circuit by only three thin, flexible conductors.

Hydraulic fluid stored in a reservoir 26 is drawn through a strainer 25 by a pump 24 driven by a motor M and is pumped to an accumulator 27 to be temporarily stored therein. A hydraulic return line to the reservoir 26 and a hydraulic line 28 communicating with the hydraulic line 21a are connected to this accumulator 27 and are respectively provided therein with electromagnetically operated valves 29 and 30C, which are connected re- 9 spectively to the contacts 23a and 23b for controllable activation thereby.

When the contact 23a is pressed and closed, the electromagnetic valve 29 is operated to close the return line to the reservoir 26, and when the contact 23b is pressed and closed, the electromagnetic valve 30C operates to open the hydraulic line 28. Electric power for these operations is provided by a power supply E through a microswitch 82 which can connect or disconnect the power supply E to or from the control circuit. The microswitch 82 is adapted to be actuated by the piston rod of the accumulator piston 27a of the accumulator 27 to connect the power supply E to the control circuit only when hydraulic fluid at a predetermined pressure has been accumulated within the accumulator 27.

The hydraulic pressure supply system and electrical control circuit of the above described organization operate in the following manner.

Referring to FIG. 9, the state of the injector shown therein is that immediately after completion of one cycle of injection operation as described herein'before, which state can be maintained by placing contact 23b of switch device 23 in its released state. Then, when contact 23a is opened, and contact 23b is closed, electromagnetic valves 29 and 30C open the hydraulic return line from hydraulic cylinder 1a to reservoir 26, whereby the interior of hydraulic cylinder 1a in injector body 1 is communicated to the return line to reservoir 26 through electromagnetic valves 30C and 29.

Consequently, hydraulic piston 2 is moved rearward by the force of spring 8 to force out the hydraulic fluid in hydraulic cylinder 1a, thereby returning this fluid toward reservoir 26. At the same time, this movement of piston 2 causes injection liquid to be drawn into injector head 12 as described hereinbefore with reference to FIG. 1.

Upon completion of the drawing in of the injection liquid, contact 23b is opened to place electromagnetic valve 30C in the closed state, and then contact 23a is closed to cause electromagnetic valve 29 to close the return line to reservoir 26. The hydraulic fluid from pump 24 thereupon is introduced under pressure into accumulator 27 to force piston 27a to retract (i.e., move toward the right as viewed in FIG. 10). When the volume of the hydraulic fluid within accumulator 27 reaches a predetermined amount, the rearward movement of piston 27a causes microswitch 82 to close and thereby connect power supply E.

Then, when contact 23b is opened, electromagnetic valve 30C is operated to open the hydraulic line between accumulator 27 and hydraulic cylinder 1a through lines 28 and 21a, whereby the hydraulic fluid which has accumulated in accumulator 27 flows into hydraulic cylinder 1a, and hydraulic piston 2 is forced forward, counter to the force of spring 8, to cause ejection of the injection liquid.

When it is desired to stop hydraulic piston 2 and, therefore, piston 17, in any position, the pressing force on contact 23b is released, whereupon the movement of these pistons 2 and 17 can be interrupted.

In the jet-injection hypodermic device as described above and. as illustrated inFIGS. 9 and 10, only a single hydraulic line and three thin, flexible conductors are necessary between the injector and the hydraulic pressure supply system. Moreover, the injector has a simple construction of light weight without hydraulic control valves. Therefore, the load imposed on the operator is substantially decreased, and fatigue due to long periods of administering injections can be reduced to a minimum.

While, in each of the above described embodiments of the invention as illustrated in FIGS. 3 and 10, a motor driven pump is used as a means for producing hydraulic pressure, it is also possible to use, instead, a pedal operated, reciprocating pump.

It should be understood, of course, that the foregoing disclosure relates to only preferred embodiments of the invention and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purposes of the discolsure, which do not constitute departures from the spirit and scope of the invention as set forth in the appended claims.

What I claim is:

1. A jet-injection hypodermic device comprising, in combination: an injector body having an injector head containing a cylinder and pump piston for drawing in a prescribed quantity of injection liquid through an inlet and ejecting, said liquid through a fine ejection orifice, said orifice being of a size to produce a skin penetrating jet of liquid; a hydraulic cylinder formed in the injector body and containing a hydraulic piston with a piston rod coupled to the pump piston for driving the same; said hydraulic piston being driven in one direction for ejecting the injection liquid by hydraulic fluid pressure supplied into the hydraulic cylinder and in the opposite direction for drawing in injection liquid by a return spring; check valve means in said injection head to permit passage of injection liquid only in the adminstering direction; hydraulic means connected by at least one hydraulic line to the injector body to supply said hydraulic fluid pressure to the hydraulic cylinder; and control means for controlling the hydraulic means thereby to control the operations of ejecting and drawing in of injection liquid.

2. A jet-injection hypodermic device comprising, in combination: an injector body having an injector head containing a cylinder and pump piston for drawing in a prescribed quantity of injection liquid through an inlet and ejecting said liquid through a fine ejection orifice; a hydraulic cylinder formed in the injector body and containing a hydraulic piston with a piston rod coupled to the pump piston for driving the same; said hydraulic piston being driven in one direction for ejecting the injection liquid by hydraulic fluid pressure supplied into the hydraulic cylinder and in the opposite direction for drawing in injection liquid by a return spring; hydraulic means connected by at least one hydraulic line to the injector body to supply said hydraulic fluid pressure to the hydraulic cylinder; and control means for controlling the hydraulic means thereby to control the operation of ejecting and drawing in of injection liquid; said hydraulic means comprising a hydraulic fluid reservoir, pump means for drawing hydraulic fluid from the reservoir and pumping the same under pressure through a hydraulic supply line to the hydraulic cylinder, a pressure accumulator connected to the hydraulic supply line, and a hydraulic discharge line for returning discharged hydraulic fluid from the hydraulic cylinder to the reservoir; and the control means comprising inlet and discharge valves installed within the injector body respectively for opening and closing the paths of hydraulic fluid between the hydraulic cylinder and the hydraulic supply and discharge lines and hand operated control means installed on the injector body for controllably operating the inlet and discharge valves.

3. The jet-injection hypodermic device as claimed in claim 2 in which the hydraulic means includes a safety valve connected to the hydraulic supply line downstream from the pump means and operating to release excessive pressure and to return released fluid to the reservoir and safety means including the pressure accumulator and connected in the hydraulic supply line, said safety means operating to permit only hydraulic fluid at a predetermined pressure to pass to the inlet valve.

4. The jet-injection hypodermic device as claimed in claim 2 in which: the hand operated control means is a spring-return mechanism manually displaceable from a normal, released position to close the discharge valve and then open the inlet valve, the discharge valve being normally open and being thus closed only when said mechanism is displaced to and beyond a first position, and the inlet valve being normally closed and being thus opened only when said mechanism is displaced to beyond 1 1 a second position of further displacement from said released position than said first position.

5. A jet-injection hypodermic device comprising, in combination: an injector body having an injector head containing a cylinder and pump piston for drawing in a prescribed quantity of injection liquid through an inlet and ejecting said liquid through a fine ejection orifice; a hydraulic cylinder formed in the injector body and containing a hydraulic piston with a piston rod coupled to the pump piston for driving the same; said hydraulic piston being driven in one direction for ejecting the injection liquid by hydraulic fluid pressure supplied into the hydraulic cylinder and in the opposite direction for drawing in injection liquid by a return spring; hydraulic means connected by at least one hydraulic line to the injector body to supply said hydraulic fluid pressure to the hydraulic cylinder; and control means for controlling the hydraulic means thereby to control the operations of ejecting and drawing in of injection liquid; said hydraulic means comprising a hydraulic fluid reservoir, pump means for drawing hydraulic fluid from the reservoir and pump ing the same under pressure through a single hydraulic line to the hydraulic cylinder, a pressure accumulator connected to the hydraulic line at a junction point thereof, a first electromagnetic valve connected in a hydraulic line betweensaid junction point and the reservoir, and a second electromagnetic valve connected in the hydraulic line between said junction point and the hydraulic cylinder; and the control means comprising first and second hand operated switches installed on the injector body for respectively operating the first and second electromagnetic valve and an electrical control circuit including said switches, the electromagnetic parts of said electromagnetic valves, and an electrical power supply for supplying power to operate the electromagnetic valves.

6. The jet-injection hypodermic device as claimed in claim 5 in which a moving part of the pressure accumulator is adapted to operate a microswitch connected in series with the power supply in the control circuit thereby to connect the power supply to the control circuit only when hydraulic pressure at a predetermined pressure has been accumulated within the accumulator.

7. A jet-injection hypodermic device comprising, in combination: an injector body having an injector head containing a cylinder and pump piston for drawing in a prescribed quantity of injection liquid through an inlet and ejecting said liquid througha fine ejection orifice;

a hydraulic cylinder formed in the injector body and containing a hydraulic piston with a piston rod coupled to the pump piston for driving the same; said hydraulic piston being driven in one direction for ejecting the injection liquid by hydraulic fluid pressure supplied into the hydraulic cylinder and in the opposite direction for drawing in injection liquid by a return spring; hydraulic means connected by at least one hydraulic line to the injector body to supply said hydraulic fluid pressure to the hydraulic cylinder; and control means for controlling the hydraulic means thereby to control the operations of ejecting and drawing in of injection liquid; wherein the return stroke of the hydraulic piston rod due to the return spring is ad-justably limited by an adjustable limiting means thereby to adjust the quantity of injection liquid drawn in, said limiting means comprising a spring retainer coaxially and slidably disposed around the piston rod in contact with one end of the return spring, the other end thereof being in contact with the hydraulic piston, said spring retainer being slidably guided in the axial direction of the piston rod and prevented from rotating and having screw threads around the periphery thereof, an adjusting ring coaxially and rotatably supported around said spring retainer and having screw threads engaged with the threads of the spring retainer, said adjusting ring being manually rotatable from the outer side of the injector thereby to adjust the position of the spring retainer with respect to said axial direction, and a stop projection fixed to the piston rod for contacting the spring retainer thereby to be limited in return movement.

References Cited RICHARD A. GAUDET, Primary Examiner J. B. MITCHELL, Assistant Examiner U.S. Cl. X.R. 

